SAP HCM P&F - Add custom infotype fields to process IT0759

Hi gurus,

I'm trying to build a simple process to update IT0759 via HRASR_DT transaction but I'm getting trouble to add certain 'custom' Z fields to my form.

Let me explain what I want to do. This infotype has a lot of Z fields that they are need to be updated but I don't know how I could to set them on form. I'm using standard SAP_PA backend service to put all standards ones (which are belonging to HCMT_BSP_PA_XX_R0759 structure) but I'm not be able to add the rest custom fields because they are not appearing in this structure.

Is there any tutorial or step-by-step guide to do something like that? I have 'a suspect' I should to use a generic/advanced servide but to be honest I don't understand very well which methods I should to implement to give my own business logic.

Kind Regards,